The present invention relates to exhaust stack pipe systems used to remove exhaust fumes from the muffler of an engine and in particular to vertical exhaust stack pipes and connections for use in agricultural or construction vehicles.
The exhaust systems of agricultural and construction vehicles include mufflers to reduce noise and emissions. The exhaust system also includes exhaust pipes to remove exhaust fumes away from the vehicle operator. For front engine vehicles, the exhaust system is typically located in the front of the vehicle. For most agricultural or construction vehicle having front engines, the exhaust system usually can not be routed to the rear of the vehicle because work attachments and other implements are often located at the rear of the vehicle. For rear engine agricultural and construction vehicles, the exhaust system usually exits above or on the side of the engine compartment rather than from the back or bottom of the engine. Thus, for an agricultural or construction vehicle it is common for a vertical exhaust stack system to be located on the top or the side of the front hood or on the top or the side of the rear engine compartment.
The muffler for the vehicle is often positioned in a horizontal or vertical orientation along the side or the top of the engine. The exhaust stack pipe extends vertically upward from the exhaust outlet stub pipe of the muffler to emit exhaust from the engine at a sufficient distance above and away from the operator or cab of the vehicle. The exhaust fumes will be dissipated quickly without being drawn into the cab, for example.
It is necessary to locate such vertically oriented exhaust stack pipes in front of or on the side of the operator or cab for front engine vehicles for various reasons previously mentioned. For example, the exhaust system can not be located under an agricultural or construction vehicle due to the need for high ground clearance and because of the possible damage resulting from unintended ground contact.
In one currently used exhaust stack system, an exhaust stack pipe is merely clamped to the vertical exhaust outlet stub pipe of the muffler with a compression-type clamp. Because the muffler usually vibrates with the engine, the compression clamp causes considerable undesirable stress concentrations on the exhaust stack pipe at the clamp line. As a result, the exhaust stack pipe is subject to fatigue and premature failure. For example, some exhaust stack pipes have prematurely failed after only a couple of hundred hours of operation. Replacing and maintaining exhaust stack systems is expensive and may also result in vehicle down time due to delays to obtain replacement parts.
As shown in FIG. 1, one currently used, vertically orientated exhaust stack pipe 12 has longitudinal slits 14 at the proximal end 18. The slits allow the proximal end of the exhaust stack pipe to be flared outward. The flared portion 16 of the exhaust stack pipe can then fit over the exhaust outlet stub pipe 20. The exhaust outlet stub pipe 20 is vertically orientated from the muffler 22, and is generally only a short pipe, about 2 or 3 inches long. The exhaust outlet stub pipe 20 usually has a constant diameter that is smaller than the flared portion 16 of the exhaust stack pipe 12. A compression clamp 24, such as a U-clamp or a ring clamp, secures the flared portion 16 of the exhaust stack pipe to the exhaust stub pipe 20 of the muffler. The clamp 24 is tightened around the flared portion 16 to provide a sealed passageway between the muffler 22 and the exhaust pipe 12 and also to mechanically hold the exhaust stack pipe 12 in a vertical position on the muffler stub pipe 20.
Unfortunately, a tight compression clamp can create stress concentrations such as hoop stress on the exhaust stack pipe. The resulting stress can lead to premature failure at the proximal end 16 of the exhaust stack pipe 12, which is already weakened by being slit and flared outward. Loosening the compression clamp 24 may reduce the hoop stress but is not a solution since a loose clamp allows exhaust fumes to leak from the exhaust outlet stub pipe. Alternatively a loose clamp may allow the exhaust stack pipe to disconnect from the exhaust outlet stub pipe 20. Permanently attaching the exhaust stack pipe to the muffler is also not a solution since the exhaust stack pipe often needs to be removed for ready access to the engine compartment.
What is desired, then, is a vertically oriented exhaust stack system which is of simple construction, but which reduces stress concentrations and premature failure at the connection of the exhaust stack pipe and the muffler. Furthermore, the connection must provide a good exhaust seal and a strong mechanical support for the vertical orientated exhaust stack pipe on the vehicle. Also, the exhaust stack pipe should be both removable and replaceable for ready access to the engine compartment.
An exhaust stack system for a muffler has an exhaust outlet stub pipe including a first tapered portion on the outer diameter of the exhaust stub pipe. An exhaust stack pipe also has a second matching tapered portion on the inner diameter at the proximal end so as to matingly seat on the first tapered portion of the exhaust stub pipe. Preferably a securing mechanism holds the exhaust stack pipe in proper orientation with the muffler stub pipe.
In a preferred embodiment, the securing mechanism includes a spring clip member. The exhaust stack pipe has a longitudinal slot near the proximal end and the muffler stub pipe has a hole in alignment with the longitudinal slot. A hooked end of the spring clip is fitted through the longitudinal slot and into the hole. The hooked end of the spring clip can slid longitudinally in the longitudinal slot and allows the exhaust stack pipe to further longitudinally settle on the outlet stub pipe.
In other embodiments, the securing mechanism can be a threaded fastener screwed through a hole in the exhaust stack pipe and into the muffler stub pipe or alternatively a self-threading screw.